Table iii



y 21, 1963 E. L. HILLIER 3,090,763

DRY BLENDING VINYL RESIN Filed Jan. 25, 1960 INVENTOR EDWARD L. H/L L IE1? av Zia ATTORNEY United States Patent Ofiice 3,090,763 Patented May 21, 1983 3,090,763 DRY BLENDING VlNYL RESIN Edward L. Hillier, Cuyahoga Falls, Ohio, nssignor to The United States Stoneware Company, Tallmadge, Ohio, a corporation of Ohio Filed Jan. 25, 1960, Ser. No. 4,406 4 Claims. (Cl. 260-23) This invention relates to an improved process of using a powdered additive with a plasticized vinyl resin to produce a iree-flowing powder, known as a dry blend.

Dry blends have been on the market for some time. Only certain types of vinyl resins and certain plasticizers have been usable in their production. When a powdering additive (described in detail hereinafter) is added to a damp, particulate mass of any extrusion grade of plasticized pearl-type vinyl resin (as hereinafter explained), the resin-plasticizer blend becomes free flowing. A blend is free flowing if it has a flow rate of at least 5 cc. per second by equipment described in ASTM D-392-38 (apparent density test). The rate of flow as there described is referred to herein, and particularly in Table V, as the "dry blend flow.

The powdering additive may be any one or more very finely divided solid materials of a large class which comprises both organic and inorganic compounds. These will be described hereinafter.

There have been various disadvantages or limitations inherent in the prior methods of producing free-flowing blends, primarily because it has been possible to use only certain resins and certain plasticizers in producing them. In the process of this invention, any pearl-type resin and any plasticizer can be used.

Furthermore, the dry blends of the prior art have not been too satisfactory. The extrudates obtained from them have often been porous, of high fish eye" content and rough surfaced, due to inadequate densification of the resin-plasticizer mass in the extruder. This can be overcome by increasing the length of the extruder working chamber or by using a higher internal working pressure. Such remedies increase the cost per unit output.

According to this invention such difficulties are overcome. The resin-plasticizer product treated with the powdering additive has a higher bulk density than that of the prior art materials. It approaches the theoretical which is the specific gravity of the product. The increase in bulk density of the dry blends obtained by the process of this invention will be illustrated by examples, in what follows.

The vinyl resins used in carrying out the invention include both homopolyrners of vinyl chloride and copolymers of vinyl chloride and any one of the many monomers with which vinyl chloride has been copolymerized to produce a resin. Such monomers include, for example, vinyl acetate, vinylidcne chloride, diethyl maleate, etc. The term "polymer" is used herein to include homopolymers and copolymers of vinyl chloride.

Many liquid plasticizers have been used with vinyl resins. The following are listed merely as illustrative:

Dimethyl phthalate Diethyl phthalate Dimethoxy ethyl phthalate Dibutyl phthalate Butyl cyclohexyl phthalate Butyl benzyl phthalate Dibutoxy ethyl phthalate 2 Di-Z-ethylbutyi phthalate Bis(diethylene glycol monoethyl cthe:)phthalate Di-n-hexyl phthalate Di-Z-ethylhexyl phthalate Diiso-octyl phthalate Di-l ethylhexyl hexahydrophthalatc Tri n-butyl phosphate Tributoxyethyl phosphate Cresyl diphenyl phosphate Z-ethylhexyl diphenyl phosphate Tricresyl phosphate Di-n-hexyl adipate Di-butyl-Z-ethoxyethyl adipate Di-Z-ethylhexyl adipate Diiso-octyl adipate Octyl decyl adipate Butyl phthallyl butyl glyeollate Ethyl phthallyl ethyl glycollate Di-n-butyl sebacate Di-2-ethylhexyl sebacate Di-2ethylhexyl azelate Methoxyethyl acetyl ricinoleate Polygiycol di-2-ethylhexanoate Polyesters of dibasic acids and diols (known as different grades of Paraplex and manufactured by Rohm & Haas Co.)

Chlorinated paraiiin Epoxidized soya oil Tetra-n-butyl thio disuccinate l3is(dimethyl benzyl)ether Any of these and any other plasticizer can be used in carrying out the invention.

The plasticizer is mixed with the resin after the resin has been heated, or while heat is being transferred to the resin to assist solvation. The plasticizer may be heated before being added to the resin. After plasticizing and preferably after cooling, the powdering additive is added to the plasticized resin, and this is all done in the same vessel as a part of one continuous operation.

The term powdering additives" is used herein to refer to solids as defined in this paragraph. Whether organic or inorganic, the powdering additive is so finely divided that it passes through a ISO-mesh screen. if of an inorganic composition, the powdcring additives are amorphous as distinguished from crystalline, and this distinction can be determined visually or microscopically. inorganic powdering additives are no more than one-tenth percent soluble in either hot or cold water. The organic powdering additives are generally less than about 5 percent soluble in the plasticizer being utilized in the blend. Although the powdering additive is not mixed with the plasticizer, if organic it is of such a nature that upon dispersing 5 parts (by weight) of the additive in parts of the plasticizer employed, there is no evidence of settiing, the additive being fine enough to form a homogeneous, stable, opaque dispersion in the plasticiaer.

The following table lists many materials of very diferent chemical compositions which were eli'ective as powdering additives, and others that were not satisfactory in the concentrations used. The different powdering additives were tested in this formula:

Parts by weight Marvinol VII-24 100.0 Butyl phthallyl butyl glycollate 75.0 Tin stabilizer 1.0 Ultramarine blue 0.l

The first column gives the water solubility for inorganic additives and the plasticizer dispersibility of organic additives as S]. (soluble or dispersible), Ins. (insoluble or non-dispcrsible), Sl. Sol. (slightly soluble or dispersible), V. Si. 501. (very slightly soluble, dispersible) and Disp. (stable, opaque dispersion). The second column indicatcs the concentration in which the material was employed in percentage, based on the weight of the vinyl polymer. The next column indicates whether or not the added material was effective as a powdering additive, the various materials in the concentrations used being rated as E (excellent), G (good), F (fair), I (poor) and B (bad). Those rated F, G or B have fiow rates in excess of 5 cc. per second. The list is not intended to be complete.

MATERIALS TESTED AS POWDERING ADDITIVES Concen- Wntor tratlnn Em- ]norganlcs soluhlllty used alone;

(P cent Ultrox ZrBl0|.....

oxmu Cellto Bios) Oroun nnnd.

Graphite In! 24 B Copper wdcr........ lus. 24 Rhombulullun. inn. 24 B Iron powder lnl. .i 24 B Aluminum powden. lnl. i 8 F-G Lnmphloc In8..... 4 E

Condentratlun used Plaatlclzer dlsperalblllty Organlcs elency Alumlnum stearute Oulelum sloarato l'inrlum nteurnw. Cadmium stnuru Load stcorato..

rm-m COLO R8 Ihtholdcysnlno eon Phtholdcynnlne lue Dlphcnyl thloearbnzono Ornsol red ('IZCI dye) O-eresol phthuleln nnsms Bakelite VYNV-2 PVC, Eseambla 2260.. lVO, Dow -4 Saran A..- Epon i000... Ethyl oellulo Illovlc A0 MISCELLANEOUS newer-magnesia Hydroqulnono allic aeld.

gliydror bonzoleu cld: -Oxynap Lholc acid. 0 onurle acid Dlphanyl carbonate. II droxylamlne hydrochloride. 0 uooso lioramcthylenetetramtne Beta naphthol Urea Sugar, grnnulate Gu tar powdered Glycol lite-notes...

According to this invention the plasticizer is added to the resin as it is being agitated by movement of the vessel containing the resin, and heat is supplied to cause absorption of the plasticizer in the resin. Then as a part of llhO same operation, the resin is preferably cooled, as by contact with a gas which is cooler than the resin. The resin should be cooled to a temperature above room temperature and below about 250" F. The powdering additive is then added, still as a part of the same operation.

Stabilizers, coloring materials, etc. can be incorporated with the resin or plasticizer, or both, in any usual manner. Dry compounding ingredients may be mixed into the resin before adding the plasticizer. Dry pigments may be mixed as a powder with the finely divided resin without being dissolved therein. Liquids may be added to the plasticizer, and finely divided solid compounding ingredients may be suspended in the plasticizer before it is mixed with the resin. Usually liquid compounding ingredients will be added to the plasticizer to insure uniform distribution throughout the resin. A finely divided compounding ingredient other than the powdering additive may he mixed with the free-flowing resin after the powdering additive has been added to it, or such a compounding ingredient may be mixed with the powdering additive before it is mixed with the resin.

The pearl-type vinyl resins that can be used in carrying out this invention, include the first three of the following four types of resins all of which are referred to herein as extrusion grades to distinguish them from Type No. 4 which includes resins all of which are soluble (about 20 percent) at room temperature in active solvents such as methyl ethyl ketone and are used as solution resins in paint and lacquer formulations. These types of resins do not include emulsionpolymerized, dispersion grade paste resins.

Type No. 1.-This type of resin is available as large agglomerates that are relatively porous. The polymer is made by the suspension or pearl process. Thirty to 100 percent of the agglomerates is retained on an 80- to 100- mesh screen. Seventy percent of an average material is retained on an SO-mesh screen. The bulk density of such agglomerates runs from 0.450 to 0.500 gram per oc. Microscopic examination shows these resin agglomerates to be spherical, dull, white and smooth. This type of resin has been used in producing dry blends, as disclosed in the prior art.

Type No. 2.This type of resin, also made by the pearl or suspension method, has most of the general characteristics of the former type. The particles are extremely large and differ from Type No. 1 in that (1) the agglomerates are retained 100 percent on an 80rnesh screen, and (2) their bulk density is higher, ranging up to 0.550 gram per oc. They have a high capacity for absorption of plasticizer and the plasticized resin can be truly free flowing. This type of resin has been used in the production of dry blends, according to the prior art.

Type No. 3.This type of resin is known as a. coldblend resin and is made by the pearl or suspension method. The agglomerates are small and they absorb large amounts of plasticizer. The bulk density is in the range of 0.3 to 0.35 gram per cc. These resins are usually mixed cold, i.e. plasticizer is added without heating. When plasticized they are not free-flowing.

Type No. 4.This type is limited to the solution-grade resins. On microscopic examination they are dense, glassy particles rather than spongy, dull particles. They are of such small particle size that no less than 20 percent will pass through a l20-mesh screen. They include (I) copolymers of vinyl chloride with at least about to percent of vinyl acetate or vinylidene chloride and (2) homopolymers of vinyl chloride of low molecular weight and an intrinsic viscosity of no more than about 0.80. They can be made by different processes and when made by the pearl or suspension type process, and only when so made, may be utilized in carrying out this invention.

Reference will be made herein to various commer i l resins and they will be identified by their trade names. Those that are listed immediately below are all made by the pearl or suspension process and are identified under the name of the manufacturer of each. Each of the following is a polyvinyl chloride homopolymer unless otherwise identified.

6 The Dow Chemical Co;

Dow l00-4 Type 1 Dow lll-4--Type l Escambia Chemical Corporation:

Escambia USS-Type llow molecular weight Escambia l200Ty=pe 1 Escambia 1225Type 1 Escambia 1250-Type l Escambia HOD-Type 2 Escambia 2225Type 2 Escambia 2250--Type 2 The Firestone Tire & Rubber Company:

Union Carbide Corporation: VYNW--Type 3-Copolymer of vinyl chloride and vinyl acetate General Tire & Rubber Company:

Vygen l0S-Type l Vygen l20-Type l Vygen l6l-Type 3 Naugatuck Chemical Company:

Marvinol VR-24-Type l Marvinol VR-33-Upe 3 Marvinol MX-240l--Type llow molecular weight Marvinol VR--26-Type llow molecular weight Monsanto Chemical Company: Opalon 300 FlvL-Type 1 Diamond Alkali Company:

Diamond PVC450-Type 1 Diamond DX35Type llow molecular weight Diamond DX-30-Type llow molecular weight Diamond 500-Type 1 Rubber Corporation of America:

Insular -Ty-pe llow molecular weight Insular 200Typc l J. P. Frank Chemical Co.:

Presto 31540Type l Presto 325-40-Type l Presto 4024tlType llow molecular weight Thompson Chemical Company: Trulon 520-Type l low molecular weight The following tables give properties of various resins.

TABLE I General Prapernes of Varrous Vmyi Resms Dimer Dry blend characteristics intrinsic nlon Bulk Burlncc Particle Rosin vlseos- 1111mm density M011, sq. 11110, cm.

lty otor cmJg. Tgnll p Ml: Flow Dow 100-4 1.22 1120 .4011 142 0103 212 Own 101 1.21 1020 .001 174 0110 212 P Rammbla 1200 1.17 104 .4110 1111 .0174 212 G Eacmnblu 22110 1.17 v low .400 123 0177+ 212 o yxun 120 1.10 044 40.1 100 0120 212 0 0011100 11001-M 1. 1a .440 4.43 1721 0104 212 G XXIX 374 .483 100 0123 212 O 1.03 417 4014 12:1 0103 212 0 1.02 401 203 340 0102 212 P 1.02 03.1 488 171 0120 212 P zux 410 400 14s 01.10 212 P 1. 01 .072 402 102 0100 212 P 1.00 v. low 007 10.1 .0177+ 212 0 1.00 1111 100 0 xxu 1.020 043 2104 0000 212 P nu 4.13 004 0:111 00117 212 P xxxx .200 4011 1211 .0100 212 0 011 .204 007 110 .0103 212 0 011 v. low 407 114 .0177+ 100 G 011 .400 4112 .0102 100 P 0.1 .1104 404 21a .0103 100 P .88 .040 041 211 .0100 100 P 1.143 11711 100 .0100 100 P 83 047 17s .0103 170 P xxxx .004 (H6 100 .0140 170 P xxxx B72 0111 1:10 0120 100 P xxx: 2100 01:1 110 .0141 212 P 1117171 017 480 210 .0004 100 P 1477 538 200 .0000 212 P Morvinoi LAX-2401. .711 .000 .041 2:14 0070 100 P Pllovio B-w .72 .020 .1124 233 .0082 100 P Marvinol V1t-20. .71 .071 .088 1711 .0007 170 P Diamond DX-iltl xxxx 1.138 606 120 .0188 170 P The 1ntr1ns1c vlscosity was determined accordmg to No powdermg addltive was used makmg these deter- ASFM Dl243-58T. The dispersion parameter defines minations.

the spread of the particle size by a single number instead of a curve; the smaller the number, the more uniform the particle size. The bulk density of the resin is given in grams per cubic centimeter as determined by ASTM TABLE II D39Z3B. These values vary somewhat from batch to bmh. The y flow is defined as G (g or Funon Temperature and Mel! Flow of Dr P (poor). The recorded dry-blend characteristics are 60 y Blends based on prior art.

Table 11 given data on blends of the following formula: Resin tongwriiim. iii iio i t" Koilcr (air oven) hot bench Dow 100-4 107 B. Goon l0] 190 B. P (s b h 0 i i v it ll n m] g y welg t arv n0 104 Exnn 011s 102 P. Resin 100.0 MnrvinolVR-Zfl 1011 E. Butyl phthallyl butyl glycollate 75.0 60 5 32553? MX-ml :a {E- '61:] 0t11,b1l-1z1er b l 1.0 Eow 11 1 -41. 100 13.

- tramnrine ue 0.1 V Titanium dioxide 3.0 ni ii iii 8'. Diamond PVC-2 180 13. Diamond 4150... 188 B. 65 Diamond 0011 1112 P. Blamong 15%41; 162 E. anion 170 E. Vyg0n105. 178 O. Vygcn 101 182 O. The purpose is to show the wide range of fusion tern- $38: 1%? 21 i3: n peratures and the melt flows of the resins to which the vYNW-d...:: Q 102 E.

invention pertains. The melt flow was a visual observation 0f the ease with which the blend melted and spread out at 430' F. in an air oven.

The following letter: are used to compare the melt flow characteristics: E, Excellent; (3, Good; F, Fair; P, Poor; B, Bad. Cenain of the resins to which the invention is applicable were examined microscopically and the results of the examination are recorded in the following table:

TABLE III The accompanying drawing illustrates quite schematically equipment that can be used. The vessel 5 is cy- Observnlions of Microscopic Examination of Varied Vinyl Resins Relative 31m Clarity of resin particle Resln Shape Largest Average Comments ODltlOl] 300 FM Nnrvlnol V 11-24.

Mnrvtnol Vii- Diamond DX KS Diamond DX-liO Vygun lit-i. l'liovlc K- VNYW-tl. Marvlnol V Not round 00% large Borne r0 shaped. o.

00% small.

Do. All small.

blizl All small. Some rod shaped 60% large.

Conguium, all particles are loose ogglomeratos.

Here the sizes are given on an arbitrary scale, the object being merely to record relative sizes.

The following table compares the volume shrinkage during fusion of various resins to which the invention is applicable; the resins being formulated as above but without any titanium dioxide.

TABLE IV Comparison of Volume Shrinkage During Fusion With Bulk Density of Blend Percent shrinkage 420 F., 12

min

Bulk donslty, gJcc.

Rcsln Gcon IOIEI'F-ZL- Morvlnol MX-M'JL. Insular 155 ow IOIH Opulon (JFM..

Escomhla H Eseitmbla i200.

The percent shrinkage was determined by volume change determined by water displacements. The bulk density of the blend is given in grams per cc. as determined by ASTM D-392-38.

The mixing of the resin and plasticizer, and then the powdering additive, is carried out in a vessel in which there is no agitator. The resin, etc. are tumbled and mixed together by moving the vessel. Thus the vessel may be shaken, but preferably its contents are tumbled by rotating it on a tilted axis. The vessel may be generally cylindrical, but vessels of other shapes may be used.

lindrical. The mouth 6 is shown as open, but in practice may be closed, and the vessel will be provided with a vent for the air or other gas. P ferably the gas is introduced at one end of the vessel and vented from the other end. There is a bull ring 9 at the lower end of the vessel, driven by the gear 10, driven in turn by the motor 11. The top end of the vessel is supported by idler 12. The plasticizer is supplied by the pipe and spray nozzle 15. Air, or other gas (hot or cold) is shown as being supplied through the conduit 17, although the air is preferably introduced through appropriate means located at the bottom of the vessel.

The resin is added to the vessel in the form of a powder or agglomerates. The vessel is not filled more than about one-third full, so that as it is rotated on its tilted axis the contents are tumbled and thoroughly mixed. The resin is preheated or heated by hot air supplied through conduit 17. Hot air is supplied to the vessel during the salvation of the 'plasticizer, whether the resin has been preheated or not. The speed of solvation will depend upon the amount of plasticizer added and the temperature of the resin, and the temperature may be any temperature above 60 F. up to the maximum temperature above which degradation commences.

After the addition of the plasticizer is completed, tum bling is continued until solvation is complete. Then cold air is blown into the vessel while tumbling if the temperature is above about 250 F., and its contents are cooled to a temperature approaching room temperature, for example, a temperature between about 60 and about 250' F. Then, preferably without interrupting the tumbling action, the powdering additive is added. It may be added all at once. For example, inside of one minute, 5 pounds of powdering additive may be added to pounds of resin-plasticizer mixture in a to ZOO-gallon vessel tilted at an angle of 15 to 30 degrees and rotated at 20 to 60 revolutions per minute.

The following examples are illustrative. The drum and its contents are most efficiently heated or cooled by blowing air or outer gas through the drum, such gas being at a temperature sufilciently higher or lower than the drum contents to produce the desired temperature change. Each of the products had a flow rate of over 5 cc. per second (ASTM D-39238) and they are therefore described as tree flowing.

EXAMPLE 1 One hundred parts (by weight) of Marvinol VR-24 once, as a powdering additive, 6 parts of Geon 121 (a,

high moleculapweight polyvinyl-chloride homopolymer which is an extremely small particle-size, dispersion grade resin). The particles or agglomeratcs of the mixture immediately disintegrated into a product which was extremely free-flowing and powdery.

Geon 121 is an emulsion polymer and a dispersion grade of vinyl resin not suited for preparation of dry blends.

EXAMPLE 2 One hundred parts (by weight) of Marvinol VR-24 was mixed in a. heated drum at 170 F. for 10 minutes,

To this was added 70 parts of tri-2-cthy1hexyl phosphate preheated to 212 F. The blend was tumbled at 170 F. for 20 minutes and then cooled to room temperature. The resulting mixture was soft, flulfy, coherent, and had no tendency to free flow. Six parts of finely divided titanium dioxide was added, all at once. The resulting mixture was free flowing and powdery.

Eh AMPLE 3 One hundred parts (by weight) of Marvinol VR-24 was tumbled in a heated drum at 190' F. for 10 minutes. To this was added, during ten minutes, 70 parts of Paraplex 6-53, 8. high molecular-weight ester polyesterplasticizer manufactured by Rohm & Haas Co. and having a gravity of 1.08. The plasticizer had been preheated to 212 F. The resultant mixture was tumbled at 190 F. for 20 minutes and then cooled to room temperature. The resultant mixture was damp, spongy and heavy. To this mixture was added 6 parts of Pliovic A (a eopolymer of polyvinylchloride and diethyl maleate manufactured by The Goodyear Tire 8: Rubber Co., which is a dispersion grade resin which is ground to a very fine particle size when manufactured). The in corporation of this resin as a powdering additive converted the mixture to a free flowing and powdery product.

The blend of this example is illustrative of the more diflicult materials from which to prepare a dry blend, due to the high viscosity and low solubility of Paraplex 6-53. It is useful for electrical insulation, gaskets, etc.,

and is non-migrating, i.e. it will not soften painted surfaces or other forms of plastics with which it is brought into contact.

EXAMPLE 4 One hundred parts of Marvinol VR-24 was mixed at 190' P. for 10 minutes. To this was added 70 parts of di-2-ethylhexyl adipate (Adipol ZEH) which had been previously heated to 212' F. The plasticizer was added during a period of 10 minutes. The resultant mixture was tumbled at 190 F. for minutes and then cooled to room temperature. The resultant mixture was flutfy and coherent with no free-flowing tendencies. To this was added, all at once, 6 parts of a finely divided precipitated calcium carbonate (Super Multifex). After mixing for 10 minutes this blend was free-flowing and powdery.

Other experiments were carried out in the same equipment using different resins, and adding 75 parts of butyl phthallyl butyl glycollate per 100 parts of the resin. The resin was first tumbled in the vessel for 10 minutes to bring it to a temperature of 170-210 F. For lower molecular weight resins 170 F. is satisfactory; for higher molecular weight resins 210' F. is recommended. Tho plasticlzer was added over a period of 10 minutes, and the mixing was continued for another 20 minutes at about 170 F. About 3.5 percent of titanium dioxide was then added, all at once, as a powdering additive and in each case the mixture immediately became a free-flowing dry blend. Data on this treatment of the different resins is included in the following table:

TABLE V Dolora tnc0r- Alter Incorporattng poratlng powdcrlng powdurtng Avaradditive additive age purl'tesin tlcio 5171!, Dry Dry lJry Dry cm. blcnrl bland blend blend flow bulk flow hulk 506.] density, see./ dcllsll). 120 cc. ;./cc. 120 cc. glee.

Icnri-typ0 resins of relallvcl lilgh molecular welt: it:

Dow 1004 .0153 20 .311 7. 5 -10 con .0172 WP 310 12.0 .5218 Fscn1nblnl250.. .0174 22 .348 7.0 .610 lisenmhin 2250.. 0177+ 12 .422 6. 0 500 V H1011 120 0122 24 .375 0. 0 .5150 Opnlon 300 FM .0134 16 .330 7. 0 630 Pearl-typo resins 01 medium molecular weight:

Dow 111-4 .0103 [1.0 .500 Exon 915 .0100 15. 0 550 Escambln 1225. .0100 0.0 .585 Diamond PVC-450 0136 10.0 .520 Pearl-typo resins 01 low molccular weight:

Escnrnbin 1200 .0103 5.0 .641 Vygen .0103 20.0 470 Diamond DX35.. .0119 12.0 060 Diamond DX30. .0138 20. 0 6T0 lllovic B50 .0082 15. 0 .542 Marvlnul VB .0090 14.0 540 can 202 .0125 14.0 .560

The dry blend densities were determined as described in ASTM D-392-38. The particle size was measured by US. Standard screen sizes. To determine the "dry blend flow," as there defined, a funnel was used as described in ASTM D392-3B and the time required for cc. of powder to How through an orifice of 16 inch was measured. The letters "WF mean that the powder has a flow rate of less than 5 cc. per second and wouldn't flow suificiently fast for commercial use. Each of the resins treated is a polyvinyl chloride homopolymer except Geon 202 which is a copolymer of vinyl chloride and vinylidene chloride manufactured by The B. F. Goodrich Company. The table shows the effect of the powdering additive on the flowing properties of the different products, comparing the ability to flow before and after being treated with the powdering additive. For certain of the resins the bulk density is given both before and after adding the powdering additive because improvement in bulk density has been found to be a particularly good indication that a dry blend is obtained.

The examples are illustrative. Variations may be made in the procedure. For instance, the temperature at which the process is carried out will depend upon the melting point of the resin, etc. The powdering additive can be added all at once, or in increments or continuously-preferably during a brief period to economize time. Different types of tumbling equipment can be used, etc.

The invention is covered in the claims which follow.

What I claim is:

l. The process of converting into powder with a flow rate in excess of 5 cc. per second, a blend of a resin pow der or aggregate and suflicient plasticizer to give a damp, particulate mass with a blend flow rate substantially less than 5 cc. per second, which resin is selected from the class consisting of pearl-type, extrusion-grade polymers of vinyl chloride, utilizing in the process a powdered additive selected from the class consisting of organic d i organic solids so finely divided as to pass through a mesh screen, said inorganic additives being amorphous as opposed to crystalline, and being no more than onetenth of one percent soluble in water, and said organic additives being less than substantially percent soluble in the plasticizer at room temperature, 5 parts of which organic additives when dispersed in 100 parts of said plasticizer forrn suspensions which are stable and remain opaque on standing; which process comprises mixing said additive and the plnsticized resin and continuing the mixing until the mixture is converted into a finely divided powder with a flow rate in excess of 5 cc. per second.

2. The process of converting into powder with a flow rate in excess of 5 cc. per second, a btend of plasticizer and a resin selected from the class consisting of pearltype, extrusion-grade polymers of vinyi chloride, which process comprises solvating plasticizer into the resin with heat in an amount sufficient to result in a damp, particulate blend which has a flow rate substantially less than 5 cc. per second, and then cooling the plasticized resin and with the resin temperature between room temperature and 250 F., mixing with it a powdering additive selected from the class consisting of organic and inorganic solids so finely divided as to pass through a 150- mesh screen, said inorganic additives being amorphous as opposed to crystalline, and being no more than one-tenth of one percent soluble in water, and said organic additives being less than substantially 5 percent soluble in the plasticizer at room temperature, 5 parts of which organic additives when dispersed in parts of said plasticizer form suspensions which are stable and remain opaque on standing, said mixing of said additive into the plasticized resin being continued until the mixture is crnverted into a finely divided powder with a flow rate in excess of 5 cc. per second.

3. The process of claim 2 in which all of the steps of the process are carried out within one vessel and heat is supplied from heated gas within the vessel and the contents of the vessel are cooled by transfer of heat to a gas within the vessel.

4. The process of claim 1 in which the powdering additive is a polyvinyl chloride homopolymer prepared by emulsion polymerization.

References Cited in the file of this patent UNITED STATES PATENTS 2,056,796 Macht et al. Oct. 6, 1936 2,835,620 Bartlett May 20, 1958 2,958,669 Hoffman Nov. 1, 1960 OTHER REFERENCES Chemical Engineering, June 1954, pages 210-217. 

1. THE PROCESS OF CONVERTING INTO POWDER WITH A FLOW RATE IN EXCESS OF 5CC. PER SECOND, A BLEND OF A RESIN POWDER OF AGGREGATE AND SUFFICIENT PLASTICIZER TO GIVE A DAMP, PARTICULATE MASS WITH A BLEND FLOW RATE SUBSTANTIALLY LESS THAN 5 CC. PER SECOND, WHICH RESIN IS SELECTED FROM THE CLASS CONSISTING OF PEARL-TYPE, EXTRUSION-GRADE POLYMERS OF VINYL CHLORIDE, UTILIZING IN THE PROCESS A POWDERED ADDITIVE SELECTED FROM THE CLASS CONSISTING OF ORGANIC AND INORGANIC SOLIDS SO FINELY DIVIDED AS TO PASS THROUGH A 150MESH SCREEN, SAID INORGANIC ADDITIVES BEING AMORPHOUS AS OPPOSED TO CRYSTALLINE, AND BEING NO MORE THAN ONE-TENTH OF ONE PERCENT SOLUBLE IN WATER, AND SAID ORGANIC ADDITIVES BEING LESS THAN SUBSTANTIALLY 5 PERCENT SOLUBLE IN THE PLASTICIZER AT ROOM TEMPERATURE, 5 PARTS OF WHICH ORGANIC ADDITIVES WHEN DISPERSED IN 100 PARTS OF SAID PLASTICIZER FORM SUSPENSIONS WHICH ARE STABLE AND REMAIN OPAQUE ON STANDING; WHICH PROCESS COMPRISES MIXING SAID ADDITIVE AND THE PLASTICIZED RESIN AND CONTINUING THE MIXING UNTIL THE MIXTURE IS CONVERTED INTO A FINELY DIVIDED POWDER WITH A FLOW RATE IN EXCESS OF 5 CC. PER SECOND. 